Clogging and filtration coefficient in a high-speed plankton sampler

Data upon water exit-velocity in an encased high-speed plankton sampler were obtained during field use and analysed; the results show that reduction in size of mouth opening allows complete avoidance of clogging under normal working conditions in temperate waters. Reduction of mouth opening has the further effect of increasing the filtration coefficient in such a way that the sampler apparentlyfilters more than the theoretical quantity of water that would be expected from the mouth area. Unobstructed flow through the net probably reduces avoidance by fast-moving plankters.